Can anyone give me a good rule of thumb to use for distinguishing these, or are they the same, and if so - which is preferred?
It's FABER or FABERE (sm)Subject: It's FABER or FABERE (sm)

FABER stands for Flexion, ABduction, and External Rotation of the hip. FABERE stands for Flexion, ABduction, External Rotation, and Extension. It could be either. Luckily, my dictators usually spell it for me.
FABER/FABERESubject: FABER/FABERE

word book as well as medical terminology book. Thanks for the help.
could it be fabere test?Subject: could it be fabere test?

although they usually pronounce that "fah-bear," I have heard it pronounced differently sometimes.
I would capitalize FABERE becauseSubject: I would capitalize FABERE because

It is found both ways in several different reference books. In the new Stedman's Abbreviation book it's fabere. The old Stedman's Abbreviation book listed it both ways, FABERE and fabere. It is an acronym, however, and the BOS 2nd edition page 7 says, "Capitalize all letters of most acronyms." It then also goes on to say, "When acronyms become words in their own right, they sometimes evolve into lowercase form." Such as the lower-case acronym laser (light amplification by stimulation emission of radiation). Is it possible that fabere has evolved into a word of its own? I don't think so, because if it was a word of its own it wouldn't be in the abbreviation book! So, I would follow the BOS recommendation and capitalize the letters of an acronym. FABERE
FABERE should be all caps nmSubject: FABERE should be all caps nm